1. Field of the Invention
The present invention relates to a gate driver, in particular, to a gate driver capable of compensating a threshold voltage of a transistor.
2. Description of Related Art
In recent years, thin film transistor (TFT) gradually develops from a mere pixel switch to circuitry applications, and this trend can be learned about from publications in international symposiums. Uniformity and properties of TFT have been improved year after year. However, it is in urgent need of employing some methods such as component structure design, circuit compensation design, and system adjustment to eliminate an inherent defect, i.e., poor reliability, of the TFT. As for a gate driver, the circumstance that a gate of an individual TFT is biased for a long time should be avoided, in order to output a stable scan voltage.
U.S. Pat. No. 6,064,713 discloses a method of forming a gate driver by using an amorphous silicon thin-film transistor (a-Si TFT). In this patent, an output signal of a next stage is used to achieve reset, an output of a preceding stage is adopted as a driving signal, and a capacitor is employed to enhance a signal. The advantage of this patent is that each TFT is biased for a short time, and thus an increase of a threshold voltage is not easily risen when the TFT is biased. However, the disadvantage of this patent is that, a driver TFT in the gate driver might be failed as the threshold voltage gradually rises due to threshold voltage accumulation. Therefore, the lifetime of the gate driver will be restricted.
Therefore, it is an urgent need of solutions in the industry to effectively improve the drive stability and prolong the lifetime of a driver.